The award was established on 3 June 1918, shortly after the formation of the Royal Air Force (RAF), with the Royal Warrant published on 5 December 1919. It was originally awarded to RAF commissioned and warrant officers, including officers in Commonwealth and allied forces. In March 1941 eligibility was extended to Naval Officers of the Fleet Air Arm, and in November 1942 to Army officers, including Royal Artillery officers serving on attachment to the RAF as pilots-cum-artillery observers. Posthumous awards were permitted from 1979.